Gautama Buddha, who attained enlightenment under the Bodhi tree in Gaya, propagated Buddhism in India in early era, but it has got a steady decline in India when Turks invade India in the early phase of medieval era. But the spreading of Buddhism from India went steady during the time of Ashoka and later spread to Asian countries and Pan Asian countries.

Buddhism is a religion of the world. It arose in and around the ancient Kingdom of Magadha which is now in Bihar. This religion is based on the teachings of Gautama Buddha. Buddhism spread outside Magadha starting in Buddha's lifetime and later with the hands of Fahien, Hiuen Tsang and Ashoka, Buddhism spread throughout the world, but in the medieval era, India showed the steady decline.

Siddhartha to Gautama Buddha
Gautama, now known as the Buddha, spent the rest of his life travelling around northeast India, propagating his knowledge. He died at eighty, leaving a flourishing monastic order and a dedicated community to continue his work. Within the 7th century B.C., Buddhism has become the largest religion in the world, having spread throughout the Mauryan Empire and the East and Southeast Asia. Buddhism takes as its goal the escape from suffering and the cycle of rebirth and the attainment of Nirvana and emphasises meditation and the observance of moral precepts.

Buddhism after Buddha
The Buddha, however did not appoint a successor, and asked his followers to work for individual salvation. The teachings of the Buddha survived only in oral traditions. The Sangha held a number of Buddhist Councils in order to reach consensus on matters of Buddhist doctrine and practice. According to the scriptures, a monk by the name of Mahakasyapa presided over the first Buddhist Council held at Rajgir (a city and a notified area in Nalanda district in Bihar). Its function was to enumerate and agree on the Buddha's actual teachings and on monastic discipline. The Second Buddhist Council is believed to have taken place at Vaishali (an ancient city, the capital of the Licchavis and the Vajjian Confederacy, presently considered as Vaishali district in Bihar). Its function was to deal with disputed monastic practices like the use of money, the drinking of palm wine, and other irregularities; the council declared these practices illicit. What is commonly called the Third Buddhist Council was held at Pataliputra (present-day Patna) and was supposedly called by Emperor Ashoka in the 3rd century B.C. Organised by the monk Moggaliputta Tissa, it was held in order to rid the sangha of the large number of monks who had joined the order because of its royal patronage. What is often called the Fourth Buddhist Council is usually believed to have been held under the patronage of emperor Kanishka at Jalandhar. It is generally believed to have been a council of the Sarvastivada School.

Philosophical Movements found in Buddhism
Following the Buddha's passing away, India witnessed many philosophical movements emerging within Buddhism. The first of these were the various Early Buddhist Schools (including Theravada). Later, Mahayana Buddhism and Vajrayana Buddhism arose.